The battery is probably on it's way out.
Recoverable, I'd say no but some people may know better. Batteries are considered consumables and generally you expect to have to get a new one every so often. I' think you've been unlucky it's only lasted a year but not alot you can do.
You may be able to get a refurbished battery for cheaper then an HP original, you might find they'll buy your old one off you.
Lot of others if you google.